Synthesis of (Co,Mg)Al₂O₄ and (Ni,Mg)Al ₂O₄ blue ceramic nano pigment by polymerized complex method

In this study, the properties of blue inorganic nano-pigments with a spinel structure were systematically investigated. We report the preparation of a blue ceramic nano-pigment and the Co and Ni substitutional effects on the blue color. MgAl₂O₄ was selected as the crystalline host network for the synthesis of cobalt and nickel-based blue ceramic nano-pigments. Various compositions of Co_xMg_1-xAl₂O ₄ and Ni_xMg_1-xAl₂O₄ (0 ≤ x ≤ 1) powders were prepared using apolymerized complex method. The obtained powder was preheated at 400°C for 5 h and then calcined at 1000°C for 5 h. XRD patterns of the (Co,Mg)Al₂O₄ and (Ni,Mg)Al₂O₄ samples showed a single phase of the spinel structure in all compositions. TEM results indicated nano-sized pigments for (Co,Mg)Al₂O₄ and (Ni,Mg)Al₂O₄ with a particle size ranging from 20 to 50 nm. The characteristics of the color tones of (Co,Mg)Al₂O₄ and (Ni,Mg)Al₂O₄ were analyzed by CIE L*a*b* measurements. In addition, the thermal stability and the binding characteristics of (Co,Mg)Al₂O ₄, (Ni,Mg)Al₂O₄ are discussed in terms of the TG-DSC and FT-IR results, respectively.